Display Device Light Blocking Pattern Parasitic Capacitance
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Solution Overview
Problem
Liquid crystal display devices with top gate type thin film transistors face issues due to parasitic capacitance caused by light blocking layers, which degrade the operational reliability by introducing static electricity and affecting the characteristics of the thin film transistor.
Innovation Solution
A display device design that includes a light blocking pattern with a coupling portion and protrusion portions, a semiconductor pattern with overlapping areas, and a specific electrical connection structure to maintain the light blocking pattern at a constant voltage, reducing parasitic capacitance and preventing light interference, thereby enhancing the reliability of the thin film transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light blocking layer is added to block light from the backlight unit, then light interference with the active layer is prevented, but parasitic capacitance is introduced due to static electricity accumulation
Solution Approach 1:
The harmful function of the light blocking layer (accumulating static electricity causing parasitic capacitance) is extracted and eliminated by removing the layer entirely. The patent replaces the conventional light blocking layer with a light blocking structure formed by patterned black matrix and color filter materials that perform light blocking without creating parasitic capacitance issues.
Solution Approach 2:
The patent converts the light blocking function into a beneficial structure by using the black matrix and color filter materials that are already present in the display device. These materials naturally block light while their conductive or semi-conductive properties allow for controlled electrical connection, transforming a harmful component into a beneficial integrated solution.
2Object-affected harmful factors
If a light blocking layer is used to prevent light interference, then the active layer is protected, but parasitic capacitance deteriorates thin film transistor characteristics
Solution Approach 1:
The harmful parasitic capacitance effect is extracted and eliminated by removing the floating light blocking layer that causes static electricity accumulation. The replacement light blocking structure using black matrix and color filter materials does not generate significant parasitic capacitance, thereby removing the harmful interaction between light blocking and electrical performance.
Solution Approach 2:
The patent introduces an intermediary electrical connection structure (conductive layer or voltage source connection) between the light blocking structure and the voltage source. This intermediary allows the light blocking structure to be electrically grounded or biased, preventing static electricity accumulation and eliminating parasitic capacitance while maintaining the light blocking function.
3Area of stationary object
If the aperture ratio is increased to improve display quality, then light transmission is enhanced, but light interference with the active layer increases
Solution Approach 1:
The light blocking function is segmented and redistributed to specific locations (between pixels and in non-display areas) using the black matrix and color filter structures. This segmentation allows the aperture ratio within pixel areas to be maximized for light transmission, while light blocking is performed in the inter-pixel regions, thereby enhancing display quality without causing light interference.
Solution Approach 2:
The light blocking function is moved from a planar layer approach to a multi-dimensional integrated structure combining the black matrix and color filter layers. This dimensional integration allows light blocking to occur at multiple levels and locations, enabling higher aperture ratios in the display area while maintaining effective light blocking where needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces parasitic capacitance and light interference, improving the operational reliability of the display device and increasing the aperture ratio of pixels by maintaining the light blocking pattern at a constant voltage and optimizing the electrical connection structure.
Implementation Method 1
a light blocking pattern disposed on the substrate and including a coupling portion extending in a first direction and a plurality of protrusion portions protruding in a second direction crossing the first direction from the coupling portion
Data Source
AI summary
Provided is a display device.The display device includes: a substrate; a light blocking pattern disposed on the substrate; a semiconductor pattern disposed on the light blocking pattern; a gate insulating layer disposed on the semiconductor pattern; a gate wiring; an interlayer insulating layer formed on the gate wiring; a first contact hole for exposing the source area; a data wiring disposed to extend in the second direction on the interlayer insulating layer and electrically connected to the source area via the first contact hole; a first passivation layer disposed on the data wiring; a second contact hole, which is disposed between the neighboring protrusion portions of the light blocking pattern so as not to overlap the light blocking pattern, and exposes the drain area; and a pixel electrode disposed on the first passivation layer and electrically connected to the drain area through the second contact hole.